What we have had recently is a lot of larger thin (32 thou) thickness boards that have had issues with SC90 diodes bouncing off the pads in the final PNP machine.
Our setup, universal instruments GC120 or quad beam 30 spindle lightning heads. This machine is usually placing the diodes.
GC11 or 7 spindle flexjet 3 on the front and a inline High force 4 on the back. Sometimes placing the diodes to avoid bouncing.
Quick Tool tooling in all machines (don't buy lasts less than a year).
What happens is when the flexjet head is placing parts the diodes can be seen flying off the board. No other parts are disturbed. The diodes are not being bumped by parts being placed. The tooling is holding the board very well and it is not moving.
Its like the head is smacking the board hard but we never see the board move. And this is the only part we ever have a issue with.
The parts are set for the minimum of 150 grams of force, Setting it for the slow place speed dose not help or only cuts the bouncing parts in 1/2. I created a super slow Z speed and it eliminated the problem but tripled the production time.
We use to be able to place SC90/SOD323 and not have this issue, or at least not this bad.
Is the small gull wing leads on SC90/SOD323 just prone to higher than normal failure rates?
SOD523 and all SOT's are OK.
Just this last week I had a long board and noticed that after moving a soft top button from the InLine 4 to the flexjet head the right 1/2 of the board had major SOD323 jumping issues where the left side was OK, moving the button back fixed the issue. Unfortunately there are no squishy buttons to be the cause on the other 2 boards we have issues with this part on.
I am at the moment open to any thoughts or ideas. This part is fast turning our inspection department in to a rework department, not a good thing.
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